One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,5)(6,8)(10,15)(11,18)(17,22)(19,24) involution — undirected(3,8)(6,7)(9,10,14,15)(11,16,18,12)(13,17,21,22)(19,23,24,20)(25,26,30,29)(27,31,33,35)(28,32,36,38)(34,39,37,40)(1,3,5,8)(2,6,4,7)(11,18)(12,16)(13,21)(17,22)(26,29)(27,33)(28,36)(39,40)(3,8)(6,7)(9,11,14,18)(10,16,15,12)(13,19,21,24)(17,23,22,20)(25,27)(26,31)(28,37)(29,35)(30,33)(32,40)(34,36)(38,39)(1,3)(2,7)(4,6)(5,8)(9,12,14,16)(10,11,15,18)(13,20,21,23)(17,19,22,24)(25,28)(26,32)(27,34)(29,38)(30,36)(31,39)(33,37)(35,40)(1,4,5,2)(3,6,8,7)(9,13,14,21)(10,17,15,22)(11,19,18,24)(12,20,16,23)(25,29,30,26)(27,35,33,31)(28,38,36,32)(34,40,37,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.